Field of the Invention
The present invention relates to a resin composition, a resist pattern-forming method and a polymer.
Discussion of the Background
Resist pattern-forming methods by photolithography are used for formation of various types of electronic device structures such as semiconductor devices and liquid crystal devices. Various resin compositions are used for these resist pattern-forming methods, and are exemplified by a radiation-sensitive resin composition for forming a resist pattern on the upper face side of a substrate, a resin composition for forming a protective film for liquid immersion lithography, which is used for forming a protective film on the upper face side of the resist film formed from the radiation-sensitive resin composition. According to the radiation-sensitive resin composition, an acid is generated in light-exposed regions upon irradiation with exposure light, e.g., a far ultraviolet ray such as an ArF excimer laser, an electron beam, etc., and a catalytic action of the acid produces a difference in rate of dissolution in a developer solution between the light-exposed regions and light-unexposed regions, thereby enabling the resist pattern to be formed on the substrate. In addition, according to the resin composition for forming a protective film for liquid immersion lithography, since the surface of the protective film formed therefrom generally exhibits water repellency, high speed scanning in liquid immersion lithography can be facilitated, leading to efficient formation of the resist pattern.
Such resin compositions are required to enable a resist pattern to be formed which exhibits not only a high resolution and superior rectangularity of cross-sectional shape, as well as low Line Width Roughness (LWR) and superior Critical Dimension Uniformity (CDU), but also a great depth of focus and exposure latitude, and are further required to form a pattern with high accuracy in a high process yield. To address the demand, the structure of the polymer contained in the resin compositions has been extensively studied, and it is known that incorporation of a lactone structure such as a butyrolactone structure and a norbornanelactone structure can enhance the adhesiveness of the resist pattern to a substrate, and improve the aforementioned performances (see Japanese Unexamined Patent Application, Publication Nos. H11-212265, 2003-5375 and 2008-83370).
At present when microfabrication of the resist pattern has proceeded to a level for a line width of no greater than 45 nm, demanded levels for the aforementioned performances have further raised.